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0 e 0. SOOYSMITH & E. L. ABBOTT.

PROCESS OF BUILDING TUNNELS 0R SHAFTS.

No. 417.288. Patented Dec. 17, 1889.

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lT/VESSES ATTORNEYS UNITED STATES PATENT OFFICE.

( IIAR LES SOOYSMITII AND EDVARD Ii. ABBOTT, OF NEV YORK, N. Y.

PROCESS OF BUILDING TUNNELS OR SHAFTS.

SPECIFICATION forming part of Letters Patent No. 417,288, dated December 17, 1889.

Application filed I ebruary 23 l 88 9 T0 ctZZ whom it may concern.-

Be it known that we, CHARLEs Soovsnrrn and EDWARD L. ABBOTT, both of the city, county, an (1 State of New York, have invented certain new and useful Improvements in the Process of Building Tunnels or Shafts, of which the following is a specification, reference being had to the accompanying drawing, forming part hereof, which is a longitudinal sectional elevation through a tunnel or excavation, showing the manner of carrying out our process.

Our invention relates to the process of excavating in earth, mud, or the like, wherein the part to be excavated is frozen to solidify it before being dug.

The object of our invention is to so improve the process of excavating that it may be performed more easily and with greater speed than has hitherto been done.

Before our present invention the idea of solidifying the inner surface of excavated tunnels by cold air for the purpose of hardening the part to be dug had already been carried out; but in that case the surface or wall at the inner end of the excavation was praotically fiat or the wall left vertical.

In carrying out our invention the excavation is kept in theform of a cone or pyramid with the apex in the direction in which the excavation is being made. In order to freeze or solidify the earth to be excavated, we place a pipe or chamber A at the apex of the excavated cone, as shown in the drawing. This pipe or chamber is supplied with cold air or other freezing-fluid by means of apipe B, that is connected with a suitable source from whence the frcezingfluid maybe supplied to the pipe A. The cold air or other freezingiiuid, being passed to the pipe A, freezes the earth in the vicinity of said pipe, and the cold air or other freezing-flu id passes from the pipe A back through the excavation, as indicated by the arrows in the drawing. If any other fluid than air is used, it is necessary to conduct it away in a separate pipe. This cold air freezes or solidifies the earth composing the inner wall of the cone to a certain depth, as indicated by the heavy section-lines a in the drawing. The worker now removes partially the frozen layer of earth in the excavation, always keeping the excavation in Serial No. 300,865- llo model.)

the shape of a cone. As the work is going on and a layer is removed, the earth thereby left exposed is continuously kept frozen,and this freezing and removing of the earth layer by layer is kept up continuously until the desired diameter at the base of the cone is produced, whereupon a lining B is made in the excavation or tunnel, which is extended in a forward direction whenever the base of the cone has reached the desired diameter. As the earth at the apex of the cone is frozen and dug away, the pipe A is gradually advanced into the earth, the freezing of the earth about the pipe taking place each time the pipe is advanced, while the remainder'of the excavation is being removed layer by layer until the desired diameter is reached. By this means we are enabled to remove within the same time a larger amount of earth than heretofore, because the part to be excavated, instead of being a mere flat wall against which the workmen operate, is a long inclined surface upon which the operators can work, and thereby the work of freezing and excavating can progress more rapidly, the workmen taking care not to remove the earth beyond the limit of frozen material. This ability to speedily excavate is due to the fact that the extent to which earth is frozen in a certain direction is not in direct proportion to the degree of cold applied to a point, but is more nearly in proportion to the area exposed to the cold. I

In order to keep the cold air in the part of the tunnel or shaft that is being excavated, we place one or more partitions D in or near the finished part of the tunnel or shaft, which prevent the sudden outflow of the coldair. These partitions may be provided with doors I) for the admission and egress of workmen, implements, and the like. A comparatively small tube (1-, or other opening, may extend from the partition D to carry back the returning air.

In practice the freezing will be kept up at the same time as the excavation and lining are taking place, making the process continuous. Care should be taken in removing the thin layers of frozen material not to approach too near the unfrozen material.

The air in the heading or freezing pipe or chamber A may be cooled by ordinary refrigcrating apparatus in any convenient way, either by the cold-air machine, in which case the air will come directly from the machine, or by air cooled by contact with coils containing cold fluid, or by placing within the freezing chamber or pipe A coils or tanks, through which a cold fluid is passed.

The apparatus shown in United States Letters Patent No. 340,161, dated April 20, 1886, might be used to advantage in carrying out our improved process.

From the above description it is seen that only one freezing pipe or chamber or bunch of freezing-pipes is used, the earth being excavated around said pipe or bunch instead of placing a series of pipes in a circle and excavating the material left between said pipes.

It is evident that instead of making the walls of the excavation in the shape of a cone the excavation could be left with parallel walls, and if the earth at the side of the freezing-chamber was not frozen to the desired diameter after the frozen material was removed the cold air could be let into the excavated part to freeze the side thereof, similar to the use herein shown with a cone. This process may be repeated until the desired diameter is obtained.

Having now described our invention, what we claim is 1. The process herein described of excavating tunnels, shafts, or the like, consisting in making an excavation, then freezing the interior surface thereof, and then removing the frozen earth from the foremost part of said excavation and continuingin succession rearward] y therefrom, the freezing process being continued where the frozen earth is removed, substantially as specified.

2. The process herein described of excavating tunnels, shafts, or the like, consisting in forming the excavation in the shape of a pyramid or cone and freezing the earth at the apex of the cone, in then removing said frozen earth from around said apex and advancing said apex and freezing the Walls of the excavation, and in then successively removing the frozen layer of earth around the excavation and advancing the apex into the earth, substantially as described.

The process herein described of excavating tunnels, shafts, or the like, consisting in first freezing the earth, then removing a part of the frozen earth,then applying cold again to the walls of the excavation and removing the earth so frozen, substantially as described,

CHARLES SOOYSMITH. EDXVARD L. ABBOTT.

Witnesses:

THEo. F. BoURNE, HARRY M. TURK. 

